Dilator

ABSTRACT

A dilator includes a hollow shaft having an outer diameter that is smaller at a distal end than at a proximal end, and a connector connected to the proximal end of the shaft. A spirally-arranged protruding portion protruding outwardly is provided on an outer peripheral surface of the shaft. The spirally-arranged protruding portion has gaps between adjacent portions of the spirally-arranged protruding portion along a longitudinal axis of the shaft. The shaft has a first position and a second position along the longitudinal axis, the second position being located distal to the first position. The outer diameter of the shaft is smaller at the second position than at the first position. An inclination angle of the spirally-arranged protruding portion relative to the longitudinal axis is different at the second position than at the first position.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application of International Application No. PCT/JP2018/011672, filed Mar. 23, 2018, which claims priority to International Application No. PCT/JP2017/012024, filed Mar. 24, 2017. The contents of these applications are incorporated herein by reference in their entirety.

BACKGROUND

The present disclosure relates to a dilator.

Dilators are known for expanding a hole formed on the wall of the patient's digestive tract and the like for the purpose of treatment. A distal end of a dilator is inserted into the hole formed on a wall, and a tapered portion is then pushed into the hole to expand the hole. Such a dilator is disclosed in, for example, Japanese Patent Application Laid-Open No. 2008-11867.

SUMMARY

When the dilator described above is very long, a rotational force and a pushing force from the hand side (proximal side) may not be well transmitted to the distal end of the dilator, and thus a hole formed on the wall of the digestive tract cannot be sufficiently expanded.

An object of the disclosed embodiments is to provide a dilator capable of easily increasing the diameter of a hole formed on the wall of the digestive tract and the like.

In order to achieve the above object, a dilator according to the disclosed embodiments includes a shaft with a hollow shape having an outer diameter that is smaller at a distal end than at a proximal end; and a grip portion provided at the proximal end of the shaft. A spirally-arranged protruding portion protruding outwardly is provided on an outer peripheral surface of the shaft, and has gaps between adjacent portions of the spirally-arranged protruding portion along a longitudinal axis of the shaft. The shaft has a first position and a second position along the longitudinal axis, the second position being located at a distal end side relative to the first position. The outer diameter of the shaft is smaller at the second position than at the first position. An inclination angle of the spirally-arranged protruding portion with respect to the longitudinal axis can be different at the second position than at the first position. For example, the inclination angle of the spirally-arranged protruding portion can be smaller at the second position than at the first position, or can be larger at the second position than at the first position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an overall view of a dilator according to the disclosed embodiments;

FIG. 2 shows a distal-end side portion of a dilator according to the disclosed embodiments;

FIG. 3 shows a distal-end side portion of a dilator according to the disclosed embodiments;

FIG. 4 shows an overall view of a dilator according to a the disclosed embodiments;

FIG. 5 shows a distal-end side portion of a dilator according to the disclosed embodiments;

FIG. 6 shows a distal-end side portion of a dilator according to the disclosed embodiments;

FIG. 7 shows a partial cross-sectional view of a distal-end side portion of a dilator according to the disclosed embodiments; and

FIG. 8 shows a distal-end side portion of a dilator according to the disclosed embodiments.

DETAILED DESCRIPTION OF EMBODIMENTS

Below, embodiments of the present disclosure will be described with reference to the figures. It is noted that the dimensions of dilators shown in the figures are merely provided to facilitate understanding of the embodiments, but do not necessarily correspond to the actual dimensions.

FIG. 1 shows an overall view of a dilator 1 according to the disclosed embodiments.

In FIG. 1, the left side in the figure corresponds to the front end side (the distal side) which is to be inserted into the body, and the right side corresponds to the base end side (the hand side, the proximal side) which is to be operated by an operator such as a surgeon.

In FIG. 1, a dilator 1 includes a multilayer body 7 including a first coil 3 having a plurality of wires wound around into a hollow shape and a second coil 5 having a single wire wound around on an outer peripheral surface 3A of the first coil 3 in a direction (clockwise, facing to the distal end) opposite to the first coil 3 (counterclockwise, facing to the distal end); and a connector 9 having a hollow shape and connected to a proximal end of the multilayer body 7.

Wires of the first coil 3 and the second coil 5 are, for example, metal wires of stainless steel, a superelastic alloy such as nickel-titanium, and the like, or resin wires. Herein, the wires will be referred to as metal wires for the sake of example.

The first coil 3 is configured such that 10 metal wires (e.g., stainless steel wires) are wound around. The first coil 3 has a hollow shape in which an inner cavity 3B is formed penetratingly extending from a proximal end to a distal end. The first coil 3 has a body portion 3C, a tapered portion 3D, and a distal portion 3E. The first coil 3 corresponds to a shaft.

The body portion 3C is located at the proximal end side of the dilator 1, and the connector 9 is connected to a proximal end thereof. Further, the body portion 3C has a substantially constant outer diameter from the proximal end thereof through a distal end.

The tapered portion 3D is located at the distal end side of the body portion 3C, and extends distally from the distal end of the body portion 3C, and is configured so as to have an outer diameter becoming smaller toward the distal end side. The tapered portion 3D corresponds to a part of the distal end side of the shaft.

The distal portion 3E is located at the distal end side of the tapered portion 3D, and extends distally from a distal end of the tapered portion 3D. Further, the distal portion 3E has a substantially constant outer diameter from a proximal end thereof through a distal end. As described above, the first coil 3 which corresponds to a shaft has a hollow shape having an outer diameter that is smaller at a distal end than at a proximal end.

The second coil 5 includes, for example, a single metal wire wound around on the outer peripheral surface 3A of the first coil 3 in a direction (clockwise, facing to the distal end) opposite to the first coil 3 (counterclockwise, facing to the distal end). Here, the metal wire is wound around closely (with small winding pitch, for example where adjacent portions are in contact with each other) at the proximal end side of the body portion 3C, and wound around with gaps between adjacent windings at the distal end side of the body portion 3C, at the tapered portion 3D, and at the distal portion 3E. The portion of the second coil 5 that is wound around with gaps provides a spirally-arranged protruding portion protruding outwardly (outermost portion of the dilator 1, the outermost surface) on the outer peripheral surface 3A of the first coil 3. The above spirally-arranged protruding portion has gaps between adjacent portions (adjacent windings of the metal wire) along an axis A of the first coil 3 (a longitudinal axis of the shaft). The screw action of the above spirally-arranged protruding portion enables the dilator 1 to be advanced even by a rotational operation of the dilator 1.

Further, a portion of the second coil 5 is configured so that inclination angles of windings of the second coil 5 wire with respect to the axis A of the first coil 3 become gradually smaller toward the tapered portion 3D and the distal portion 3E from the body portion 3C. For example in FIG. 1, θ1>θ2>θ3>θ4. That is, the inclination angle θ3 at a second position P2 is configured so as to be smaller than the inclination angle θ2 at a first position P1 along the axis A. It is noted that the second position P2 is located distal to the first position P1, and an outer diameter of the shaft (first coil 3) is smaller at the second position P2 than at the first position P1.

Further, with regard to the metal wire of the second coil 5, the amount of gap (space) between adjacent windings of the metal wire (the length of the gap in a direction of the axis A) is gradually decreased toward the proximal end side thereof at the body portion 3C. This configuration enables the stiffness of the dilator 1 (the multilayer body 7) along the axis direction to be gradually changed so that the dilator 1 can easily enter into an approach pathway even when the pathway meanders.

The length of a dilator is, for example, 2000 mm, preferably 1600 mm to 2500 mm; the length of the distal portion 3E is, for example, 10 mm, preferably 0 to 100 mm; and the length of the tapered portion 3D is, for example, 30 mm, preferably 5 to 100 mm. The inner diameter of the distal end of the first coil 3 is, for example, 0.7 mm, preferably 0.4 to 1.0 mm; and the inner diameter of the proximal end of the first coil 3 is, for example, 1.5 mm, preferably 1.0 to 3.0 mm. The outer diameter of the distal end of the second coil 5 is, for example, 1.84 mm, preferably 0.8 to 3.0 mm; and the outer diameter of the proximal end of the second coil 5 is, for example, 2.64 mm, preferably 1.4 mm to 5.0 mm. Further, the diameters of the metal wires of the first coil 3 are, for example, 0.21 mm, preferably 0.1 to 0.5 mm, and the diameter of the metal wire of the second coil 5 is, for example, 0.36 mm, preferably 0.1 to 0.5 mm.

Further, in the dilator shown in FIG. 1, an inclination angle (θ1) of the second coil 5 (the spirally-arranged protruding portion) at the body portion 3C is about 70°, and an inclination angle (θ4) of the second coil 5 (the spirally-arranged protruding portion) at the distal portion 3E is about 60°, and the ratio of them (θ1/θ4) is 1.17. It is noted that the inclination angle (θ1) of the second coil 5 (the spirally-arranged protruding portion) at the body portion 3C is preferably 14 to 87°, and the inclination angle (θ4) of the second coil 5 (the spirally-arranged protruding portion) at the distal portion 3E is preferably 7 to 82°, and the ratio of them (θ1/θ4) preferably ranges from 1.06 to 12.4.

The connector 9 as a grip portion is a portion through which an operator pushes the dilator into the body, and/or performs a rotational operation. A distal end of the connector 9 is connected to the proximal end of the first coil 3 and the proximal end of the second coil 5. The connector 9 is made of a resin, and has a hollow shape having an inner cavity in communication with the inner cavity 3B of the first coil 3.

In the dilator 1, the spirally-arranged protruding portion (the second coil 5) protruding outwardly is provided on the outer peripheral surface 3A of the first coil 3 which corresponds to a shaft, and has gaps between adjacent portions along the axis A of the first coil 3. This configuration enables the dilator to be advanced not only by a conventional pushing operation, but also by a rotational operation of the spirally-arranged protruding portion.

Further, for the spirally-arranged protruding portion (the second coil 5) of the dilator 1, the inclination angle at the second position P2 is configured to be smaller than that at the first position P1 along the axis A. It is noted that the second position P2 is located distal to the first position P1, and corresponds to a position in which the outer diameter of shaft is smaller than at the first position P1. Therefore, the inclination angles of the spirally-arranged protruding portion are larger at a portion where the outer diameter of the first coil 3 which corresponds to a shaft is relatively large. This enables the spirally-arranged protruding portion to be firmly caught on a target object (for example, the digestive tract such as stomach, and liver). This, in turn, can prevent free rotation of the dilator 1 at the portion where the outer diameter of the first coil 3 which corresponds to a shaft is relatively large.

Further, the first coil 3 as a shaft having the tapered portion 3D at a part of the distal end side can lead to smooth expansion of a hole.

Further, a shaft comprised of the first coil 3 having a plurality of metal wires wound around into a hollow shape can improve the flexibility of the shaft and the transmissibility of torque. Further, a spirally-arranged protruding portion comprised of the second coil 5 having a single metal wire wound around on the outer peripheral surface 3A of the first coil 3 can be easily formed, and can ensure the flexibility of the distal end of the dilator 1 by virtue of the elasticity of the second coil 5, and can improve the torquability. Further, wires of the first coil 3 are wound in a direction opposite to the wire of the second coil 5. Therefore, even when the dilator 1 is rotated in a direction to open the first coil 3, a force is applied in a direction to close the second coil 5 to prevent opening of the first coil 3. This allows a force applied to the connector 9 of the dilator 1 to be transmitted to the distal end side.

Next, an example of operating modes of the above dilator will be described.

First, a target object is punctured with an introducer needle to open a hole. Subsequently, a guide wire is inserted into an inner cavity of the introducer needle, and then the introducer needle is withdrawn.

Next, the proximal end of the guide wire is inserted into an inner cavity of the above dilator, and then the dilator is inserted. Subsequently, the dilator is pushed in while rotating a shaft to expand the hole at a punctured portion. During this, the tapered portion moves forward by virtue of the screw action of the spirally-arranged protruding portion by a rotational operation of the shaft and others, enabling the tapered portion to smoothly expand the hole.

FIG. 2 shows a distal-end side portion of a dilator 10 according to the disclosed embodiments.

In FIG. 2, the left side in the figure corresponds to the front end side (the distal side) which is to be inserted into the body, and the right side corresponds to the base end side (the hand side, the proximal side) which is to be operated by an operator such as a surgeon.

It is noted that the dilator 10 basically has the same structure as the dilator 1. Therefore, the same number is given to the same member, and detailed description will be omitted.

In FIG. 2, a dilator 10 includes a multilayer body 17 including the first coil 3 having a plurality of metal wires wound around into a hollow shape and the second coils 5 having a single metal wire wound around on the outer peripheral surface 3A of the first coil 3 in a direction (clockwise, facing to the distal end) opposite to the first coil 3 (counterclockwise, facing to the distal end); and a connector 9 having a hollow shape and connected to a proximal end of the multilayer body 17 (see FIG. 1). However, the dilator 10 differs from the dilator 1 in that the dilator 10 has a distal-end portion 6 instead of the distal portion 3E of the first coil 3 of the dilator 1. In the dilator 10, the first coil 3 having the distal-end portion 6 provided at the distal end corresponds to a shaft.

The distal-end portion 6 is formed by casting a solder material (a silver-tin solder material, a gold-tin solder material, or the like) into the distal end of the hollow coil body 3, and has a substantially tubular hollow shape. Further, the distal-end portion 6 has a flat (smooth) surface while the distal end of the multilayer body 7 has an uneven surface.

In the dilator 10, a portion of the second coil 5 is also configured so that inclination angles of windings of the second coil 5 wire with respect to the axis A of the first coil 3 become gradually smaller toward the tapered portion 3D and the distal portion 3E from the body portion 3C. In FIG. 10, θ1>θ2>θ3 as in the dilator 1. That is, the inclination angle θ3 at the second position P2 is configured so as to be smaller than the inclination angle θ2 at the first position P1 along the axis A. It is noted that the second position P2 is located distal to the first position P1, and an outer diameter of the shaft (first coil 3) is smaller at the second position P2 than at the first position P1.

The dilator 10 having this configuration can produce similar effects as the dilator 1. Further, the distal-end portion 6 having a flat surface is connected to the distal end of the multilayer body 17. This configuration can further improve insertability into a punctured portion by first pressing the dilator against the punctured portion, and then pushing and rotating the dilator thereinto.

FIG. 3 shows a distal-end side portion of a dilator 20 according to the disclosed embodiments.

In FIG. 3, the left side in the figure corresponds to the front end side (the distal side) which is to be inserted into the body, and the right side corresponds to the base end side (the hand side, the proximal side) which is to be operated by an operator such as a surgeon.

In FIG. 3, the dilator 20 includes a multilayer body 27 including a hollow coil body 21, a coil body 22, a coil body 23, a coil body 24, and a coil body 25; and a connector 9 (FIG. 1) having a hollow shape and connected to a base end of the multilayer body 27.

The hollow coil body 21 is configured such that a plurality of metal wires (for example, 10 wires) are wound around into a tubular hollow shape. In FIG. 3, the dotted line (the innermost among the three dotted lines) represents the common inscribed line of the hollow coil body 21, and an inner cavity 21B is formed inside the common inscribed line of the hollow coil body 21.

A distal end of the coil body 22 is located proximal to a distal end of the hollow coil body 21, and the coil body 22 is configured such that a plurality of metal wires (for example, 16 wires) are wound around on an outer peripheral surface 21A of the hollow coil body 21 into a tubular hollow shape. The plurality of metal wires of the coil body 22 are wound around in the same direction (counterclockwise, facing to the distal end) as the hollow coil body 21. In FIG. 3, the dotted line (the intermediate among the three dotted lines) represents the common inscribed line of the hollow coil body 22.

A distal end of the coil body 23 is located proximal to the distal end of the hollow coil body 22, and the coil body 23 is configured such that a plurality of metal wires (for example, 23 wires) are wound around on an outer peripheral surface 22A of the hollow coil body 22 into a tubular hollow shape. The plurality of metal wires of the coil body 23 are wound around in a direction (clockwise, facing to the front end) opposite to the coil body 22 (counterclockwise, facing to the front end). In FIG. 3, the dotted line (the outermost among the three dotted lines) represents the common inscribed line of the hollow coil body 23.

The coil body 22 is twistedly formed on the outer peripheral surface 21A of the hollow coil body 21, and the coil body 23 is twistedly formed on the outer peripheral surface 22A of the coil body 22. This means that the hollow coil body 21 and the coil body 22 which correspond to the shaft have a hollow shape having an outer diameter that is smaller at a distal end than at a proximal end.

The coil body 24 is configured such that a single element wire is wound around with gaps between adjacent windings on the outer peripheral surface 21A of the coil body 21 in a direction (clockwise, facing to the distal end) opposite to the coil body 21 (counterclockwise, facing to the distal end). The coil body 25 is configured such that a single metal wire is wound around with gaps between adjacent windings on the outer peripheral surface 22A of the coil body 22 in a direction (clockwise, facing to the distal end) opposite to the coil body 22 (counterclockwise, facing to the distal end).

In the dilator 20, the multilayer body 27 has a stepped and tubular hollow shape without the tapered portion.

It is noted that the hollow coil body 21 and the coil body 22 correspond to the shaft and the first coil, and the coil bodies 24 and 25 correspond to the spirally-arranged protruding portion and the second coil.

In the hollow coil body 21, the coil body 22, and the coil body 23, each wire is wound around closely while in the coil body 24 and the coil body 25, each wire is wound around with gaps between adjacent windings. The coil body 24 provides a spirally-arranged protruding portion protruding outwardly (outermost portion of the dilator 20, the outermost surface) on an outer peripheral surface 21A of the hollow coil body 21, and the coil body 25 provides a spirally-arranged protruding portion protruding outwardly (outermost portion of the dilator 20, the outermost surface) on an outer peripheral surface 22A of the coil body 22. The above spirally-arranged protruding portions have gaps between adjacent portions (adjacent windings of the metal element wire) along an axis A of the hollow coil body 21.

The wires of the hollow coil body 21, the coil body 22, the coil body 23, the coil body 24, and the coil body 25 may be metal wires made of stainless steel, a superelastic alloy such as nickel-titanium or the like. They shall not be limited to metal wires, but may be resin wires.

Further, the coil body 24 and the coil body 25 are configured so that inclination angles of windings of the wires with respect to the axis A become gradually smaller from the proximal end side to the distal end side (from the side of the coil body 22 to the side of the hollow coil body 21). In FIG. 3, θ5>θ6>θ7. That is, the inclination angle at a second position P4 is configured so as to be smaller than that at a first position P3 along the axis A. It is noted that the second position P4 is located distal to the first position P3, and corresponds to a position of the shaft having an outer diameter smaller than at the first position P3.

In the dilator 20, the spirally-arranged protruding portions (the coil bodies 24 and 25) are configured so that the inclination angles are smaller at the second position P4 than at the first position P3 along the axis A. It is noted that the second position P4 is located distal to the first position P3, and corresponds to a position of the shaft having an outer diameter smaller than at the first position P3. Therefore, the inclination angles of the spirally-arranged protruding portion are larger at the coil body 22, which corresponds a portion where the outer diameter of the shaft is relatively large. This enables the spirally-arranged protruding portion to be firmly caught on a target object (for example, the digestive tract such as stomach, and liver). This, in turn, can prevent free rotation of the dilator 20 at the coil body 22, which corresponds to a portion where the outer diameter of the shaft is relatively large.

Further, a shaft (the first coil) composed of the hollow coil body 21 and the coil body 22 each including a plurality of metal wires wound around into a hollow shape can improve the flexibility of the shaft and the transmissibility of torque via the shaft. Further, a spirally-arranged protruding portion (the second coil) composed of the coil body 24 including a single metal wire wound around on the outer peripheral surface 21A of the hollow coil body 21 and the coil body 25 wound around on the outer peripheral surface 22A of the coil body 22 can be easily formed, and can ensure the flexibility of the distal end of the dilator 20 by virtue of the elasticity of the second coil, and can improve the torquability. Further, the wires of the hollow coil body 21 and the coil body 22 are wound in a direction opposite to the wires of the coil body 24 and the coil body 25. Therefore, even when the dilator 20 is rotated in a direction to open the hollow coil body 21 and the coil body 22, a force is applied in a direction to close the coil body 24 and the coil body 25 to prevent opening of the hollow coil body 21 and the coil body 22. This allows a force applied to the connector 9 of the dilator 20 to be transmitted to the distal end side.

FIG. 4 shows an overall view of a dilator 30 according to the disclosed embodiments.

In FIG. 4, the left side in the figure corresponds to the front end side (the distal side) which is to be inserted into the body, and the right side corresponds to the base end side (the hand side, the proximal side) which is to be operated by an operator such as a surgeon.

In FIG. 4, the dilator 30 includes a shaft 31, a spirally-arranged protruding portion 32, and a connector 9 connected to a proximal end of the shaft 31.

The shaft 31 has a hollow shape in which an inner cavity 31A is formed penetratingly extending from a proximal end to a distal end. The shaft 31 also has a body portion 33, a tapered portion 34, and a distal portion 35.

There is no particular limitation for materials of the shaft 31 and the spirally-arranged protruding portion 32, as long as they can ensure the flexibility of the tapered portion 34 and the distal portion 35 as well as biocompatibility. For example, the following materials can be used: stainless steel, superelastic alloy materials such as nickel-titanium alloys, or synthetic resins such as polyvinyl chloride resin, urethane resin, polyolefin resin, polyamide resin, and fluororesin.

The body portion 33 is located at the proximal end side of the dilator 30, and the connector 9 is connected to a proximal end thereof. Further, the body portion 33 has a substantially constant outer diameter from the proximal end thereof through the distal end.

The tapered portion 34 is connected to the distal end of the body portion 33, and extends from that distal end to the distal end side, and has a shape tapered toward the distal end side. That is, the tapered portion 34 is configured so that the outer shape of the distal end side is smaller than that of the proximal end side.

The distal portion 35 is connected to a distal end of the tapered portion 34 and extends from that distal end to the distal end side. The distal portion 35 has a substantially constant outer diameter from a proximal end thereof through a distal end. As described above, the shaft 31 has a hollow shape having an outer diameter that is smaller at a distal end than at a proximal end.

The spirally-arranged protruding portion 32 is provided on an outer peripheral surface 31B of the shaft 31 so as to be protruded outwardly (outermost portion of the dilator 30, the outermost surface). The spirally-arranged protruding portion 32 is provided at a distal-end side portion of the body portion 33, at the tapered portion 34, and at the distal portion 35, and has gaps between adjacent portions along an axis A of the shaft 31. That is, the adjacent portions of the spirally-arranged protruding portion 32 are spaced from each other. The spirally-arranged protruding portion 32 is integrally formed with the shaft 31 by casting or the like.

Further, the spirally-arranged protruding portion 32 is configured so that inclination angles of adjacent portions of the spirally-arranged protruding portion 32 with respect to the axis A of the shaft 31 become gradually smaller toward the tapered portion 34 and the distal portion 35 from the body portion 33. In FIG. 4, θ8>θ9>θ10>θ11. That is, the inclination angle θ10 at a second position P6 is configured so as to be smaller than the inclination angle θ9 at a first position P5 along the axis A. It is noted that the second position P6 is located distal to the first position P5, and corresponds to a position of the shaft 31 having an outer diameter that is smaller than at the first position P5.

Further, pitches T1 and T2 of the spirally-arranged protruding portion 32 at the tapered portion 34 are configured to be constant. That is, pitches T1 and T2 between adjacent portions along the axis A of the spirally-arranged protruding portion 32 at the tapered portion 34 are configured to be substantially constant as shown in FIG. 4.

In the dilator 30, the spirally-arranged protruding portion 32 protruding outwardly is provided on the outer peripheral surface 31B of the shaft 31, and has gaps between adjacent portions along the axis A of the shaft 31. This configuration enables the dilator to be advanced not only by a conventional pushing operation, but also by a rotational operation of the spirally-arranged protruding portion 32.

Further, in the dilator 30, the spirally-arranged protruding portion 32 is configured so that the inclination angles of the spirally-arranged protruding portion 32 are smaller at the second position P6 than at the first position P5 along the axis A. It is noted that the second position P6 is located distal to the first position P5, and corresponds to a position of the shaft 31 having an outer diameter that is smaller than at the first position P5. Therefore, the inclination angles of the spirally-arranged protruding portion 32 are larger at a portion in which the outer diameter of the shaft 31 is relatively large. This enables the spirally-arranged protruding portion 32 to be firmly caught on a target object (for example, the digestive tract such as stomach, and liver). This, in turn, can prevent free rotation of the dilator 30 at the portion in which the outer diameter of the shaft 31 is relatively large.

Further, the shaft 31 having the tapered portion 34 at a part of the distal end side can lead to smooth expansion of a hole. In addition, the inclination angles of the spirally-arranged protruding portion 32 are larger at a portion in which the outer diameter of the shaft 31 is relatively large. This enables the spirally-arranged protruding portion 32 to be firmly caught on a target object (for example, the digestive tract such as stomach, and liver) to prevent free rotation of the dilator 30.

Further, the pitches T1 and T2 of the spirally-arranged protruding portion 32 at the tapered portion 34 are configured to be constant. This enables a distance of advance to be maintained constant at the tapered portion 34 when the dilator 30 is rotationally operated.

FIG. 5 shows a distal-end side portion of a dilator 40 according to the disclosed embodiments.

In FIG. 5, the left side in the figure corresponds to the front end side (the distal side) which is to be inserted into the body, and the right side corresponds to the base end side (the hand side, the proximal side) which is to be operated by an operator such as a surgeon.

In FIG. 5, the dilator 40 includes a shaft 41, a spirally-arranged protruding portion 42, and a connector 9 connected to a proximal end of the shaft 41 (see FIG. 4). The material(s) of the shaft 41 and the spirally-arranged protruding portion 42 is/are the same as that/those of the shaft 31 and the spirally-arranged protruding portion 32 of the dilator 30.

The shaft 41 has a hollow shape in which an inner cavity 41A is formed penetratingly extending from a proximal end to a distal end. The shaft 41 has a body portion 43 and a tapered portion 44. The dilator 40 differs from the dilator 30 in that the dilator 40 does not have the distal portion.

The body portion 43 and the tapered portion 44 have the same configurations as the body portion 33 and the tapered portion 34 of the dilator 30. Further, the spirally-arranged protruding portion 42 is provided on an outer peripheral surface 41B of the shaft 41 so as to be protruded outwardly (outermost portion of the dilator 40, the outermost surface). The spirally-arranged protruding portion 42 is provided at a distal-end side portion of the body portion 43 and at the tapered portion 44, and has gaps between adjacent portions of the spirally-arranged protruding portion 42 along an axis A of the shaft 41. That is, the adjacent portions of the spirally-arranged protruding portion 42 are spaced from each other. The spirally-arranged protruding portion 42 is integrally formed with the shaft 41 by casting or the like.

Further, the spirally-arranged protruding portion 42 is configured so that inclination angles of the spirally-arranged protruding portion 42 with respect to the axis A of the shaft 41 become gradually smaller toward the tapered portion 44 from the body portion 43. In FIG. 5, θ12>θ13>θ14. That is, the inclination angle θ14 at a second position P8 is configured so as to be smaller than the inclination angle θat a first position P7 along the axis A. It is noted that the second position P8 is located distal to the first position P7, and corresponds to a position of the shaft 41 having an outer diameter that is smaller than at the first position P7.

Further, pitches T3 and T4 of the spirally-arranged protruding portion 42 at the tapered portion 44 are configured to be constant. That is, the pitches T3 and T4 between adjacent portions of the spirally-arranged protruding portion 42 at the tapered portion 34 are configured to be substantially constant as shown in FIG. 4.

In the dilator 40, the spirally-arranged protruding portion 42 protruding outwardly is provided on the outer peripheral surface 41B of the shaft 41, and has gaps between adjacent portions along the axis A of the shaft 41. This configuration enables the dilator 40 to be advanced not only by a conventional pushing operation, but also by a rotational operation of the spirally-arranged protruding portion 42.

Further, in the dilator 40, the spirally-arranged protruding portion 42 is configured so that the inclination angles of the spirally-arranged protruding portion 42 are smaller at the second position P8 than at the first position P7 along the axis A. It is noted that the second position P8 is located distal to the first position P7, and corresponds to a position of the shaft 41 having an outer diameter that is smaller than at the first position P7. Therefore, the inclination angles of the spirally-arranged protruding portion 42 are larger at a portion in which the outer diameter of the shaft 41 is relatively large. This enables the spirally-arranged protruding portion 42 to be firmly caught on a target object (for example, the digestive tract such as stomach, and liver). This, in turn, can prevent free rotation of the dilator 40 at the portion in which the outer diameter of the shaft 41 is relatively large.

Further, the shaft 41 having the tapered portion 44 at a part of the distal end side can lead to smooth expansion of a hole. In addition, the inclination angles of the spirally-arranged protruding portion 42 are larger at a portion in which the outer diameter of the shaft 41 is relatively large. This enables the spirally-arranged protruding portion 42 to be firmly caught on a target object (for example, the digestive tract such as stomach, and liver) to prevent free rotation of the dilator 40.

Further, the pitches T3 and T4 of the spirally-arranged protruding portion 42 at the tapered portion 44 are configured be constant. This enables a distance of advance to be maintained constant at the tapered portion 44 when the dilator 40 is rotationally operated.

FIG. 6 shows a distal-end side portion of a dilator 50 according to the disclosed embodiments.

In FIG. 6, the left side in the figure corresponds to the front end side (the distal side) which is to be inserted into the body, and the right side corresponds to the base end side (the hand side, the proximal side) which is to be operated by an operator such as a surgeon.

In FIG. 6, the dilator 50 includes a shaft 51, a spirally-arranged protruding portion 52, and a connector 9 connected to a proximal end of the shaft 51 (see FIG. 4). The material(s) of the shaft 51 and the spirally-arranged protruding portion 52 is/are the same as that/those of the shaft 31 and the spirally-arranged protruding portion 32 of the dilator 30.

The shaft 51 has a hollow shape in which an inner cavity 51A is formed penetratingly extending from a proximal end to a distal end. The shaft 51 also has a tapered portion 54. The dilator 50 differs from the dilator 30 in that the dilator 50 does not have either the distal portion or the body portion. That is, the shaft 51 has a tapered shape having an outer diameter gradually decreasing from a proximal end to a distal end throughout the entire length. This means that the shaft 51 has a hollow shape having an outer diameter that is smaller at a distal end than at a proximal end.

The spirally-arranged protruding portion 52 is provided on an outer peripheral surface 51B of the shaft 51 so as to be protruded outwardly (outermost portion of the dilator 50, the outermost surface). The spirally-arranged protruding portion 52 is provided at a distal-end side portion of the tapered portion 54, and has gaps between adjacent portions along an axis A of the shaft 51. That is, the adjacent portions of the spirally-arranged protruding portion 52 are spaced from each other. The spirally-arranged protruding portion 52 is integrally formed with the shaft 51 by casting or the like.

The spirally-arranged protruding portion 52 is configured so that inclination angles of the spirally-arranged protruding portion 52 with respect to the axis A of the shaft 51 become gradually smaller toward the distal end side from the proximal end side at the tapered portion 54. In FIG. 6, θ15>θ16>θ17. That is, the inclination angle θ17 at a second position P10 is configured so as to be smaller than the inclination angle θ16 at a first position P9 along the axis A. It is noted that the second position P10 is located distal to the first position P9, and is a position of the shaft 51 having an outer diameter that is smaller than at the first position P9.

Further, pitches T5, T6, and T7 of the spirally-arranged protruding portion 52 at the tapered portion 54 are configured to be constant. That is, the pitches T5, T6, and T7 between adjacent portions of the spirally-arranged protruding portion 52 at the tapered portion 54 are configured to be constant as shown in FIG. 6. It is noted that in FIG. 6, pitches of the spirally-arranged protruding portions 52 at portions other than these having pitches indicated are also configured to be constant.

In the dilator 50, the spirally-arranged protruding portion 52 protruding outwardly is provided on the outer peripheral surface 51B of the shaft 51, and has gaps between adjacent portions of the spirally-arranged protruding portion 52 along the axis A of the shaft 51. This configuration enables the dilator 50 to be advanced not only by a conventional pushing operation, but also by a rotational operation of the spirally-arranged protruding portion 52.

Further, in the dilator 50, the spirally-arranged protruding portion 52 is configured so that the inclination angles of the spirally-arranged protruding portion 52 are smaller at the second position P10 than at the first position P9 along the axis A. It is noted that the second position P10 is located distal to the first position P9, and is a position of the shaft 51 having an outer diameter that is smaller than at the first position P9. Therefore, the inclination angles of the spirally-arranged protruding portion 52 are larger at a portion in which the outer diameter of the shaft 51 is relatively large. This enables the spirally-arranged protruding portion 52 to be firmly caught on a target object (for example, the digestive tract such as stomach, and liver). This, in turn, can prevent free rotation of the dilator 50 at the portion in which the outer diameter of the shaft 51 is relatively large.

Further, the shaft 51 having the tapered portion 54 can lead to smooth expansion of a hole. In addition, the inclination angles of the spirally-arranged protruding portion 52 are larger at a portion in which the outer diameter of the shaft 51 is relatively large. This enables the spirally-arranged protruding portion 52 to be firmly caught on a target object (for example, the digestive tract such as stomach, and liver) to prevent free rotation of the dilator 50.

Further, the pitches T5, T6, and T7 of the spirally-arranged protruding portion 52 at the tapered portion 54 are configured to be constant. This enables a distance of advance to be maintained constant at the tapered portion 54 when the dilator 50 is rotationally operated.

FIG. 7 shows a distal-end side portion of a dilator 60 according to the disclosed embodiments.

In FIG. 7, the left side in the figure corresponds to the front end side (the distal side) which is to be inserted into the body, and the right side corresponds to the base end side (the hand side, the proximal side) which is to be operated by an operator such as a surgeon. It is noted that the same reference number is given to the same member as the dilator 30, and description thereof is omitted.

In FIG. 7, the dilator 60 includes the shaft 31, a spirally-arranged protruding portion 62, and the connector 9 connected to the proximal end of the shaft 31.

The spirally-arranged protruding portion 62 is provided on the outer peripheral surface 31B of the shaft 31 so as to be protruded outwardly (outermost portion of the dilator 30, the outermost surface). The spirally-arranged protruding portion 62 is provided at a distal-end side portion of the body portion 33, at the tapered portion 34, and at the distal end portion 35, and has gaps between adjacent portions of the spirally-arranged protruding portion 62 along the axis A of the shaft 31. That is, the adjacent portions of the spirally-arranged protruding portion 62 are spaced from each other. The spirally-arranged protruding portion 62 is integrally formed with the shaft 31 by casting or the like.

Further, the spirally-arranged protruding portion 62 is configured so that the inclination angles of the spirally-arranged protruding portion 62 with respect to the axis A of the shaft 31 become gradually larger toward the tapered portion 34 and the distal portion 35 from the body portion 33. In FIG. 7, θ18<θ19<θ20<θ21. That is, the inclination angle θ20 at a second position P12 is configured to be larger than the inclination angle θ19 at a first position P11 along the axis A. It is noted that the second position P12 is located distal to the first position P11, and is a position of the shaft 31 having an outer diameter that is smaller than at the first position P11.

In the dilator 60, the spirally-arranged protruding portion 62 protruding outwardly is provided on the outer peripheral surface 31B of the shaft 31, and has gaps between adjacent portions of the spirally-arranged protruding portion 62 along the axis A of the shaft 31. This configuration enables the dilator 60 to be advanced not only by a conventional pushing operation, but also by a rotational operation of the spirally-arranged protruding portion 62.

It is noted that in the dilator 60, the spirally-arranged protruding portion 62 is configured so that the inclination angles of the spirally-arranged protruding portion 62 are larger at the second position P12 than at the first position P11 along the axis A. It is noted that the second position P12 is located distal to the first position P11, and is a position of the shaft 31 having an outer diameter that is smaller than at the first position P11. Therefore, the inclination angles of the spirally-arranged protruding portion 62 are larger at a portion in which the outer diameter of the shaft 31 is relatively small. This enables the spirally-arranged protruding portion 62 to be firmly caught on a target object (for example, the digestive tract such as stomach, and liver). This, in turn, can prevent free rotation of the dilator 60 at the portion in which the outer diameter of the shaft 31 is relatively small.

Further, the shaft 31 having the tapered portion 34 at a part of the distal end side can lead to smooth expansion of a hole. In addition, the inclination angles of the spirally-arranged protruding portion 62 are larger at a portion in which the outer diameter of the shaft 31 is relatively small. This enables the spirally-arranged protruding portion 62 to be firmly caught on a target object (for example, the digestive tract such as stomach, and liver) to prevent free rotation of the dilator 60.

Hereinbefore, the embodiments of the present disclosure are described, but the present disclosure shall not be limited to these embodiments. Rather, various modifications may be made.

For example, the first coils 3 and 21 are each described as a hollow coil body including 10 wires in the aforementioned embodiments, but the number of wires shall not be limited to 10. The number may be one or more.

Further, the coil body 22 is described as a coil body including 16 wires in the aforementioned embodiments, but the number of wires shall not be limited to 16. The number may be one or more.

Further, the coil body 23 is described as a coil body including 23 wires in the aforementioned embodiments, but the number of wires shall not be limited to 23. The number may be one or more.

Further, the distal-end portion 6 of the dilator 10 is described to be formed by casting a solder material into the distal end of the multilayer body 17. However, the outer periphery of the second coil 5 and/or the first coil 3 in the vicinity of the distal end portion of the multilayer body 17 may be ground to form the distal-end portion 6 having a flat surface.

Furthermore, the distal-end portion 6 is described to be fixed to the distal end of the multilayer body 17 of the dilator 10, but the distal-end portion may be fixed to the distal end of the multilayer body 27 of the dilator 20, the distal end of the shaft 31 of the dilator 30 or dilator 60, the distal end of the shaft 41 of the dilator 40, and the distal end of the shaft 51 of the dilator 50.

Further, the outer peripheries of the multilayer bodies 7, 17, and 27, the shafts 31, 41, 51, and 61, and the spirally-arranged protruding portions 32, 42, 52, and 62 may be coated with a resin(s). For example, as shown in FIG. 8, the outer peripheries of the shaft 31 and the spirally-arranged protruding portion 32 of the dilator 30 may be coated with a resin 36. The resin 36 can improve slidability to prevent damage to a living body tissue. When the outer periphery of the shaft 31 is coated with the resin 36, a portion where the body portion 33, the tapered portion 34, and the distal portion 35 are coated with the resin 36 corresponds to the shaft 31, and a portion protruding outwardly from the outer peripheral surface 31B of the above shaft 31 corresponds to the spirally-arranged protruding portion 32. Examples of the resin 36 include, for example, biocompatible resin materials such as polyamide resin and fluororesin, or hydrophilic coating materials, and the like. The resin 36 has a thickness of, for example, 0.1 to 300 μm. Further, the shafts 31, 41, and 51 and the spiral protruding portions 32, 42, and 52 are configured integrally, but may be configured as separate bodies.

Further, as described above, the second coils 5, 24, and 25 and the spirally-arranged protruding portions 32, 42, 52, and 62 are configured so that the inclination angles of the spirally-arranged protruding portions are gradually decreased, but the inclination angles can be configured to be stepwisely decreased. Further, the shafts 31, 41, and 51 and the spiral protruding portions 32, 42, 52, and 62 are configured integrally, but may be configured as separate bodies. Further, the first positions P1, P3, P5, P7, P9, and P11 and the second positions P2, P4, P6, P8, P10, and P12 are not limited to the positions described above, and the first and second positions may be located at any positions as long as the second position is located distal to the first position, and an outer diameter of the shaft is smaller at the second position than at the first position.

Furthermore, the shaft may have various types of coating on the side of the surface thereof (including a portion between the shaft and the spirally-arranged protruding portion) other than or in addition to the resin 36. Examples of the coating include, for example, a protective film on the surface of the shaft (representative example: a plating film), an underlying film for improving adhesiveness between the shaft and the spirally-arranged protruding portion, and the like.

Preferably, the spirally-arranged protruding portion is not configured to serve as a blade. The dilators according to the present embodiments are intended for expanding a hole pre-formed on a target object (for example, the wall of the digestive tract such as the patient's stomach). Therefore, if the spirally-arranged protruding portion serves as a blade, living body tissues at the inner surface of the hole may be damaged.

For this reason, the spirally-arranged protruding portion preferably does not have a sharp edge at an end portion on a radially outer side of the shaft in a cross-section (for example, on a cross-section perpendicular to the spiral direction of the spirally-arranged protruding portion as shown in FIG. 4). That is, the above end portion preferably has an area having a shape including an obtuse angle or a curve (for example, a curve constituting a part of a circle or an ellipse). Thus, the spirally-arranged protruding portion is configured so as not to cut living tissue when dilating a hole pre-formed on a target object. 

What is claimed is:
 1. A dilator comprising: a hollow shaft having an outer diameter that is smaller at a distal end of the shaft than at a proximal end of the shaft; a spirally-arranged protruding portion provided on an outer peripheral surface of the shaft, the spirally-arranged protruding portion protruding radially outward from the shaft and having gaps between adjacent portions of the spirally-arranged protruding portion along a longitudinal axis of the shaft; and a grip portion provided at the proximal end of the shaft, wherein: the outer diameter of the shaft is larger at a first position of the shaft along the longitudinal axis than at a second position of the shaft along the longitudinal axis, the second position being located distal to the first position in a distal end side of the shaft, and an inclination angle of the spirally-arranged protruding portion with respect to the longitudinal axis is different at the second position than at the first position.
 2. The dilator according to claim 1, wherein a part of the distal end side of the shaft has a tapered shape having an outer diameter decreasing in a distal direction.
 3. The dilator according to claim 2, wherein pitches of the spirally-arranged protruding portion are constant in the part of the distal end side of the shaft having a tapered shape.
 4. The dilator according to claim 1, wherein the shaft includes a first coil having a wire wound around into a hollow shape.
 5. The dilator according to claim 1, wherein the spirally-arranged protruding portion includes a second coil having a wire wound around on the outer peripheral surface of the shaft.
 6. The dilator according to claim 1, wherein: the shaft includes a first coil having a wire wound around into a hollow shape, and the spirally-arranged protruding portion includes a second coil having a wire wound around on the outer peripheral surface of the shaft, and the wire of the first coil is wound in a direction opposite to the wire of the second coil.
 7. The dilator according to claim 1, wherein the inclination angle of the spirally-arranged protruding portion with respect to the longitudinal axis is smaller at the second position than at the first position.
 8. The dilator according to claim 1, wherein the inclination angle of the spirally-arranged protruding portion with respect to the longitudinal axis is larger at the second position than at the first position. 